This project is a continuation of work on the function and regulation of the amino acid taurine in the mammalian heart. The detailed mechanism of the stimulated influx of taurine into the heart caused by cyclic AMP will be investigated. Studies of the cardiac pharmacology of taurine, including the relationship between taurine and amrinone, and the protection effect of taurine on the lesions of cardiomyopathic Syrian hamsters, will be continued. Guanidinoethyl sulfonate will be used to lower taurine levels in the heart in order to study abnormalities induced by defective taurine regulation.